The invention relates to a method for operating a motor vehicle, air-conditioning of the motor vehicle, which is driven by an engine, being started by at least one air-conditioning device by an activation signal when the motor vehicle is deactivated.
Stationary heaters and stationary air-conditioning devices are already largely known in the related art. They are used to already change a motor vehicle in the direction of an air-conditioning state desired by the driver when the driver has not yet activated the motor vehicle. In an improvement of this functionality, it has been proposed to also already render air-conditioning devices, which are driven by an engine or use the engine, usable before the driver actually enters the motor vehicle. For this purpose, it is possible to use, for example, a radio remote control of the motor vehicle which provides the motor vehicle with a corresponding activation signal. The engine in the motor vehicle is activated then or at a time provided with the activation signal. The same applies to the air-conditioning device which begins to cool or heat the motor vehicle as required. When the driver then reaches the motor vehicle, he can ideally find the desired climate in the motor vehicle, but at least already a pre-air-conditioned motor vehicle. It goes without saying that other signals can also be used as the activation signal, for example in the manner of a scheduler which is coupled to a corresponding system belonging to the driver, in particular, the air-conditioning being effected in response to specific appointments.
However, in the case of such operating methods when (pre)air-conditioning a motor vehicle, in particular after a so-called “remote start”, the problem arises of the motor vehicle possibly being situated in a closed space, for example a garage. If the engine is now activated, exhaust gases occur which may be hazardous in excessively high concentrations. Therefore, the known methods provide for the air-conditioning period and therefore the period in which the engine is operated to be limited to a predetermined, fixed, maximum engine operating time.
However, the air-conditioning performance is extremely restricted as a result of this time limitation. In the event of extreme heat or cold, the result may be that the target temperature of the air-conditioning cannot be reached.